Doses of swine flu vaccine for young children are recalled in Md., Va.

Some doses of swine flu vaccine for young children are being recalled in Maryland and Virginia.

The issue is not one of safety, according to the federal Centers for Disease Control and Prevention. Instead, the strength of the vaccine had dropped slightly after it was shipped, the CDC said. Officials said the vaccine is still supposed to work, and there's no need to get the shot again.

Affected are certain lots of single-dose syringes for kids 6 months to 35 months old made by the pharmaceutical company Sanofi Pasteur. It's a voluntary, nationwide recall.

"The vaccine potency is only slightly below the 'specified' range. The vaccine in these lots is still expected to be effective in stimulating a protective response despite this slight reduction in the concentration of antigen. There is no need to re-administer a dose to those who received vaccine from these lots," according to the CDC.

Kids younger than 10 years are supposed to get a second shot a month after the first anyway, and should still do so, according to the CDC.

Maryland Health Department spokesman David Paulson said the state has received 10,300 doses of vaccine from the affected lots. They went to 48 providers, though not to any local health departments. Officials don't know yet how many of those doses have been used, and they did not immediately provide information on where the affected providers are located.

Health officials in Maryland and Virginia said they are notifying doctor's offices and other vaccinators of the recall and the CDC guidance.

District officials said they are checking whether the city received any of the affected lots.